1. Photoluminescence of Mesoporous Silica Film Impregnated with an Erbium Complex Oun-Ho Park †, Jae Young Bae, Ji-in Jung, and Byeong-Soo Bae Laboratory of Optical Materials and Coating (LOMC), Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea E-mail: oh-park@kaist.ac.kr http://www.sol-gel.net/lomc Research direction The 5 th International Meeting of Pacific Rim Ceramic Societies September 29 – October 2 2003, Nagoya Congress Center, Nagoya, Japan Sample preparation of the mesoporous silica film impregnated with ErQ Conclusions References FT-IR Spectra  Since planar optical amplifiers have a smaller interaction length with respect to erbium- doped fiber amplifiers, higher erbium concentration is required to obtain a sufficient optical gain.  high doping levels of erbium quench the fluorescence emission and reduce the performance of the amplifier.  Theoretically, the most effective method for uniform dispersion is the periodic arrangement of erbium ions in a matrix when high doping levels of Er 3+ ions are required.  In this study, we impregnate Er complex into mesoporous silica film, and then measure the photoluminescence for 1.5  m amplification.  Oun-Ho Park, Se-Young Seo, Ji-In Jung, Jae Young Bae, and Byeong-Soo Bae, J. Mater. Res. 18[5], 1039 (2003)  Jae Young Bae, Ji-in Jung, Oun-Ho Park, Byeong-Soo Bae, Koodali T. Ranjit, L. Kevan, Studies in Surface Science and Catalyst 146, 65 (2003)  Jae Young Bae, Oun-Ho Park, Ji-in Jung, Koodali T. Ranjit, Byeong-Soo Bae, Micropor. Mesopor. Mat., in press  Preparation of mesoporous silica films - Precursor : Tetramethylorthosilicate (TMOS) - Solvent : Methanol (CH 3 OH) - Surfactant : n-Cetyltrimethylammonium Chloride [CH 3 (CH 2 ) 15 N(CH 3 ) 3 ]Cl (CTACl)  Transparent mesoporous silica films are successfully fabricated using a sol-gel spin coating method.  The obtained mesoporous silica films have hexagonal structure with 2 nm pore size.  Er complex is homogeneously impregnated into the mesoporous silica films by an immersing technique, and its concentration can be easily controlled by changing the concentration of Er complex solution. Schematic Structure  PL intensity increases as the concentration of ErQ solution increases due to the impregnation of ErQ into the pore. Thermogravimetric Analysis  Abrupt weight losses take place at 280 & 310 o C due to the desorption and the decomposition of CTACl, respectively.  Temperature profile is determined to calcine the residual organic surfactants effectively. XRD Result Photoluminescence  Pore size : 2 nm  Expected molecular size of ErQ : >1 nm  It is expected that the impregnated ErQ molecules are homogeneously distributed due to the periodic pore arrangement.  FT-IR spectra of (a) as-synthesized and (b) calcined mesoporous silica films  Residual OH and organic templates are almost removed. Synthesis of Mesoporous Silica Film  XRD patterns of (a) as-synthesized and (b) calcined hexagonal mesoporous silica films Characterization of Mesoporous Silica Film Optical Properties of Mesoporous Silica Film Impregnated with ErQ Temperature Profile for Calcination N 2 AdsorptionEr distribution & ConcentrationConcentration Effect MicrostructureHigh Resolution TEM images  Obtained mesoporous silica films are optically transparent in the range of visible wavelength.  TEM cross-sectional images of perpendicular (a, b) and through (c) the pores of hexagonal mesoporous silica thin films  Pore size : ~ 2 nm Transmittance  Erbium 8-hydroxyquinoline (ErQ) was incorporated into the mesoporous silica films by impregnation. The silica films were placed into 10 ml of 1.5  10 -3 –1.5  10 -2 M erbium 8-hydroxyquinoline in ethanol. Ethanol was removed by flowing nitrogen gas over the sample. ErQ Dissolve ErQ in EtOH Immersion of mesoporous silica film Ultrasonic treatment Surface Cleaning EtOH Mesoporous silica film Water Decomposition of CTACl Desorption of CTACl 433 ± 2 nm (a) (b) Average Roughness : 2 nm 50nm 20nm (c)(b)(a) Substrate  (a) SEM & (b) ARM Images Surface area (m 2 /g)Pore size(nm) ErQ undoped9202.1 ErQ doped7252.0  ErQ is impregnated into the pore!  Depth profile and composition was obtained by RBS measurements.  Er is impregnated up to ~10 21 ions/cm 3.  PL is linearly proportional to erbium atomic density., which implies  No concentration quenching was found up to ~10 21 ions/cm 3 of erbium concentration.  ErQ impregnated mesoporous silica film shows a clear 1.5  m photoluminescence.  Impregnation of ErQ into the pore is confirmed by N 2 adsorption.  Homogeneous distribution of ErQ in depth is confirmed by RBS measurement.  High concentration of erbium is impregnated without concentration quenching  PL is linearly proportional to the erbium concentration. ErQ concentration in ethanol solution Er/Si ratio Er atomic density (cm -3 ) 1.5  10 -3 N 0.012 1.8  10 20 0.7  10 -2 N 0.052 0.8  10 21 1.5  10 -.2 N 0.12 1.8  10 21